Generally, an electrochromic device (ECD) displays or stores using electrochromism and is used in a smart window, a display device, and a micro-battery, etc.
Here, the electrochromism means a phenomenon that when a voltage is applied, an electrolytic oxidation or reduction reaction and colorizing/decolorizing is reversibly performed.
That is, the electrochromic device displays a new color or generates a transmission/non-transmission window as an absorption amount of light increases by an oxidation-reduction reaction or an electron transition which loses or obtains an electron when a voltage is applied to an electrochromic material that is a light transmitting body.
FIG. 1 is a view illustrating an embodiment of a related art general electrochromic device.
As shown in FIG. 1, the related art electrochromic device includes a structure having an electrochromic layer 5 formed between a lower transparent substrate 1 to which a lower conductive layer 2 is adhered and an upper transparent substrate 3 to which an upper conductive layer 4 is adhered. Here, the upper/lower conductive layer is made of an indium-tin-oxide (ITO) material having a transparent conductive material. The electrochromic layer 5 is colored/decolored by a voltage and may be made of a material having a transmission characteristic or non-transmission characteristic. At this time, if the electrochromic layer 5 is made of a material having a specific color, the specific color (for example, green color) can be embodied by a voltage. The lower conductive layer 2 and the upper conductive layer 4 can be formed on an entire surface of the lower transparent substrate 1 and the upper transparent substrate 3, respectively.
Therefore, the electrochromic layer 5 has a transmission characteristic by the voltage applied to the upper/lower conductive layers 2 and 4, so that visible light incident to the lower transparent substrate 1 can be emitted to the outside through the upper transparent substrate 3.
If a voltage opposite to the voltage applied before is applied, the electrochromic layer 5 has non-transmission characteristic, so that visible light incident to the lower transparent substrate 1 can be not emitted to the outside through the upper transparent substrate 3.
When the electrochromic device having such characteristics is applied to a vehicle window or a building window, etc., the outside can be seen or not through the window as needed.
Further, as described above, the electrochromic device can be used as a display device for displaying a specific color.
However, because the related art electrochromic device is required for a long time in colorizing/decolorizing, it is not proper for a display characteristic which should instantly display a color, so that it has been not in the spotlight.
On the other hand, a display device may have a structure shown in FIG. 2. The display device may be used as, for example, a display device of a car and display a number, a character, or an image.
FIG. 2 is a view illustrating an embodiment of a display device employing a related art general phosphor.
As shown in FIG. 2, the display device employing the related art phosphor includes a plurality of first electrode groups 7 arranged in the first direction on a transparent substrate 6, a phosphor layer 8 formed on the transparent substrate 6 in which the first electrode group 7 is arranged, a black dielectric layer 9 formed on the phosphor layer 8 to improve a contrast of the phosphor layer 8, and a plurality of second electrode groups 10 formed on the black dielectric layer 9 and arranged in the second direction perpendicular to the first electrode group 7.
Here, the first electrode group 7 is made of ITO having a transparent conductive material so that the color generated in the phosphor 8 may be transmitted and exposed to the outside through the transparent substrate 6. On the other hand, the second electrode group 10 may be made of a transparent or opaque conductive material because the color generated in the phosphor 8 is not transmitted by the black dielectric layer 9 and emitted to only the transparent substrate 6 side.
The phosphor layer 8 is made of a phosphorous material that converts electricity to light and the set color is generated by a predetermined voltage. For example, in a case where the phosphor layer 8 is made of a phosphorous material having red (R) color, when a voltage is applied to the phosphor layer 8, red (R) color can be generated. Therefore, as the phosphor layer 8 is made of a phosphorous material to embody a specific color, the specific color can be generated.
On the other hand, in a case of embodying diverse colors as needed, the phosphor layer 8 can be made of a phosphorous material having corresponding colors. For example, a surface of the phosphor layer 8 is composed of a plurality of pixels in which phosphorous materials having the respective red (R) color, green (G) color, and blue (B) color are arranged in a matrix shape, diverse colors are generated by the respective pixels having the respective color phosphorous materials by a voltage applied between a plurality of first electrode groups 7 vertically arranged and a plurality of second electrode groups 10 and a predetermined image can be displayed by the diverse colors.
As described above, the electrochromic device can control transmission/non-transmission and the display device using a phosphor can embody a predetermined image.
However, a display device having a transmission/non-transmission function, that is, a window function and a display function has been not yet suggested.